Warming tray



FIG. 1 is a perspective view of a warming tray embodying the new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a rear elevational view thereof; and

FIG. 6 is a left-end elevational view thereof. 

The ornamental design for a warming tray, as shown. 